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Density. How tightly the atoms are packed together in an object. Density At the conclusion of our time together, you should be able to:. Define density Calculate the density of a given object if given the volume and mass
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Density How tightly the atoms are packed together in an object
DensityAt the conclusion of our time together, you should be able to: Define density Calculate the density of a given object if given the volume and mass Calculate the volume or mass if the density is given with the volume or mass
Density • Density = mass volume • Mass = the amount of matter in an object • Volume = the amount of space the object takes up • Units = g/mL (liquid) OR g/cm3 (solid)
Platinum Mercury Aluminum DENSITY - an important and useful (qualitative) intensive physical property 13.6 g/cm3 21.5 g/cm3 2.7 g/cm3
Density Calculations M D V Cover up whatever unit you are solving for, the two units remaining will show you how to solve the problem.
Density Calculations • Regularly Shaped Solid : mass = balance volume = measure (l x w x h) • Irregularly Shaped Solid: mass = balance volume = water displacement
Density Calculations • Liquid: volume = read graduated cylinder mass = tare graduated cylinder, mass liquid
ProblemA piece of copper has a mass of 57.54 g. It is 9.36 cm long, 7.23 cm wide, and 0.95 mm thick. Calculate density (g/cm3). M D V
Strategy 1. Get dimensions in common units. 2. Calculate volume in cubic centimeters. 3. Calculate the density.
SOLUTION 1. Get dimensions in common units. 2. Calculate volume in cubic centimeters. 3. Calculate the density. (9.36 cm)(7.23 cm)(0.095 cm) = 6.4 cm3 Note only 2 significant figures in the answer!
PROBLEM: Mercury (Hg) has a density of 13.6 g/cm3. What is the mass of 95 mL of Hg in grams? In pounds?
Strategy First, note that1 cm3 = 1 mL 1. Use density to calculate mass (g) from volume. 2. Convert mass (g) to mass (lb) Need to know conversion factor = 454 g / 1 lb
Strategy 1. Convert volume to mass 2. Convert mass (g) to mass (lb)
Learning Check Osmium is a very dense metal. What is its density in g/cm3 if 50.00 g of the metal occupies a volume of 2.22 cm3? 1) 2.25 g/cm3 2) 22.5 g/cm3 3) 111 g/cm3
Solution 2) Placing the mass and volume of the osmium metal into the density setup, we obtain D = mass = 50.00 g = volume 2.22 cm3 = 22.522522 g/cm3 = 22.5 g/cm3
Learning Check Osmium is a very dense metal. What is its density in g/cm3 if 50.00 g of the metal occupies a volume of 2.22 cm3? 1) 2.25 g/cm3 2) 22.5 g/cm3 3) 111 g/cm3
Volume Displacement A solid displaces a matching volume of water when the solid is placed in water. 33 mL 25 mL
Learning Check What is the density (g/cm3) of 48 g of a metal if the metal raises the level of water in a graduated cylinder from 25 mL to 33 mL? 1) 0.2 g/ cm3 2) 6 g/m3 3) 252 g/cm3 33 mL 25 mL
DensityLet’s see if you can: Define density Calculate the density of a given object if given the volume and mass Calculate the volume or mass if the density is given with the volume or mass
Learning Check Which diagram represents the liquid layers in the cylinder? (K) Karo syrup (1.4 g/mL), (V) vegetable oil (0.91 g/mL,) (W) water (1.0 g/mL) 1) 2) 3) K W V V K W W V K
Learning Check The density of octane, a component of gasoline, is 0.702 g/mL. What is the mass, in kg, of 875 mL of octane? 1) 0.614 kg 2) 614 kg 3) 1.25 kg
Learning Check If blood has a density of 1.05 g/mL, how many liters of blood are donated if 575 g of blood are given? 1) 0.548 L 2) 1.25 L 3) 1.83 L 4) 548 L
Learning Check A group of students collected 125 empty aluminum cans to take to the recycling center. If 21 cans make 1.0 pound of aluminum, how many liters of aluminum (D = 2.70 g/cm3) are obtained from the cans? (1 kilogram = 2.2 pounds) 1) 1.00 L 2) 2.00 L 3) 4.00 L
Water has a density of 1.0 g/ml and mercury (Hg) has a density of 13.6 g/ml. Which is heavier, a quart of water or a quart of mercury? If we have equal volumes of two different substances, then the one with the greater density will have the greater mass.
Which is heavier, a ton of feathers or a ton of bricks? Neither • Which is larger? Feathers • If two objects have the same mass, the one with the higher density will be smaller.